1. Field of the Invention
The present invention relates to a sheet conveying apparatus which conveys a sheet and an image forming apparatus provided with the same.
2. Description of the Related Art
An image forming apparatus which transfers a toner image while conveying a recording material from below to above through a first conveyance path disposed in parallel to the side surface of a casing and fixes the toner image in a fixing device disposed substantially right above a transferring portion has been put to practical use (Japanese Patent Application Laid-open (JP-A) No. 2007-128005).
In the image forming apparatus disclosed in JP-A No. 2007-128005, a second conveyance path is interposed between the first conveyance path and the side surface of the casing. The recording material having the toner image fixed thereon is switched back to be conveyed from above to below through the second conveyance path, and then, is fed to the transferring portion again.
In the above-described image forming apparatus, a rotatable cover unit is generally disposed in the casing. When the cover unit is opened, the second conveyance path is released. Releasing the second conveyance path is directed to taking out a sheet jammed on the second conveyance path. In addition, a guide unit forming the second conveyance path in cooperation with the cover unit is rotatably disposed in the casing inside of the cover unit. The cover unit is rotated, and then, the guide unit is rotated, so that the first conveyance path for the sheet is released.
In the case where the guide unit is disposed inside of the cover unit, the guide unit should be desirably pushed to a position where the first conveyance path is closed in abutment against the cover unit to be closed in order to prevent forgetting to close the guide unit.
In JP-A Nos. 2003-167469 and 2008-292517 has been proposed a configuration in which a jammed sheet is removed, and then, a guide unit is automatically moved to a position where a conveyance path is closed in mechanical association with a cover unit to be closed.
Here, the cover unit and the guide unit are disposed with a slight play with respect to the casing. As a consequence, a relative position between a second roller disposed in the cover unit and a first roller disposed in the guide unit is shifted by the play. When the sheet is conveyed by the second roller and the first roller while being nipped therebetween, the sheet is skew fed or is shifted widthwise onto either side, therefore, the precision of the conveying the sheet is not high. As the precision of the conveying the sheet is not high, an obverse image and a reverse image are deviated from each other.
In order to solve such a problem, it may be construed that the cover unit and the guide unit are fixed to a common frame by the use of precise bearings without any play. However, in such a case, the second roller need be precisely fixed to the cover unit, and further, the first roller need be precisely fixed to the guide unit, thereby increasing cost.
The present invention provides a sheet conveying apparatus which can convey the sheet with the high precision.